As a general rule, continuously cast billets with a diameter of 230 millimeters (9 inches) are used as the raw material for seamless pipes. Billet shears cut them into the desired lengths. In the case of alloyed types of steel that cannot be cut using shears, the billets are removed from the production line and cut up using a carbide-tipped saw. The cut-to-length billets are then heated in a rotary hearth furnace to a deformation temperature of about 1280° C (2336 ° F).

voestalpine Tubulars gets the billets for manufacturing pipes and tubes from a related voestalpine company in Donawitz (Austria), which is one of the world’s technologically most advanced steel plants.

Billet Storage: 

Preheating Furnace:

Carbide Saws:

Billet Shears:

Rotary Hearth Furnace:

The piercing mill is used to subject the solid round cut-to-length billets to a rolling process, with an output speed of 1 meter per second. They are held against an inner tool and shaped to form shells with a specific wall thickness and diameter.

Using a crimping press, the pierced hollow shells are attached to the end of the mandrel bars and then deformed to create the mother tubes. This is accomplished on the push bench: The mandrel bars are pushed through a stand of three-roll cages, which have decreasing cross section. As a result, the hollow shells are elongated over the mandrel bars to form a tube up to 17 times longer than its original length. After the mother tubes have been formed, the mandrel bars, which are still inside the tubes, are removed. The wall thickness of the mother tubes is checked along the entire length using radiometric-measuring equipment. The tubes are then placed in the re-heating furnace.

Crimping Press:

Push Bench:

Roller Breakage Control:

Reeler:

Radiometric Wall Thickness Control:

In the re-heating furnace, the mother tubes are again heated to the temperature required for the stretch reducing process. To ensure that the mother tubes are heated uniformly, they are rotated constantly while in the furnace. 

The mother tubes, which have been re-heated and descaled using a water blast, are deformed in a stretch-reducing mill with 28 stands, until they have the final desired diameter and wall thickness. Various controls ensure optimal yield of the mother tube and that the required tolerances are met. The wall thickness of the resulting tubes is checked along the entire length using radiometric equipment. The results of these inspections are output graphically and documented. Following cooling on 90-meter-long rake type cooling beds, the ends are cropped and the tubes are cut into processing lengths.

Radiometric Wall Thickness Inspection:

Rake-Type Cooling Bed:

Cold Saws:

Depending on specification material is further processed in the OCTG Processing Plant or the Boiler Tube Plant.